Quicktime .mov screen recording bad quality

Quicktime Screen Recording Becomes Blurry. You may have noticed that when you scale an image, the quality usually degrades. ...zooming is stretching or shrinking a screen recording to display it at a different size than the original recording. This can cause the on-screen video to rapidly degrade and appear blurry or distorted.

So you can
Fix Glitching Screen Recording In After Effects if you Export your file in 4k or HD formaat from Quicktime player.

You can find it in menu Archive -> Export As -> 4k